The Second International Symposium on Immunotoxins, scheduled for June 14th-16th, 1990 at the Grosvenor Resort at Lake Buena Vista, Florida, will provide the only forum for exchange of scientific information on the mechanism of action of peptide toxins of plant bacterial and fungal origin and on the protein engineering design problems unique to immunotoxins for therapy of cancer and leukemia. Specific unique aspects of this meeting will be: (1) The first presentation, at an international meeting, of the 3-dimensional structure of several proteins (ricin and pseudomonas exotoxin) using a new computer/projector system for simultaneous viewing by a large audience. (2) The first review of genetic engineering of peptide toxins by all active major groups worldwide. (3) The only meeting with a workshop facilitating immunotoxin development including molecular biologists, protein chemists, process-development scientists, pharmacologist, regulatory affairs people and clinicians. (4). The first review of all clinical trials in immunotoxins to this date. The long term consequences of such a meeting are to encourage new scientist to enter the field of toxin research and to speed the development of new immunotoxin for treatment of cancer and leukemia. This is the only forum (held every other year) which is focused on an in depth scientific.study of immunotoxin research and development with over 300 participating scientists and clinicians.